Considering that 'carriers' are balanced as an order of magnitude stronger than 'unescorted flag ships', yes, ablative is worth getting. It is also worth backing up with heavier armor if you can, but if you are going up against remnants and the like, ablative is far superior.

Mind you, if you're playing ABEM, there's a slight difference between the description and the functionality. Ablative armor there DOES NOT have any bonus to laser resistance - I suspect this is because Powered armor already has a 50% resistance to energy weapons on top of its normal functionality.